Lots of great tips already. Get a lot of GOOD QUALITY practice time behind your rifle. Don’t beat yourself up over this. Most folks aren’t nearly as good of a shot as they’d like to think they are and I’d venture to say 80% or better are not nearly as good on offhand shots as they’d like to think. Like 257 said get a pre-shot routine just like with a bow. Follow it religiously til you don’t even have to think about doing it. It just happens. The biggest reason most folks aren’t as good as they think is simply because they don’t practice it enough. Get to Know your rifle. I try to use a bag whenever possible. They help a ton.

More practice

Practice shooting at long distances, practice breathing while shooting, and get something like a timney trigger. Like anything else ,practice and you will improve.

I’ve trained with the worlds greatest soldiers and I have neen baffled by how some folk who never picked up a gun can become some of the worlds greatest marksman (following instruction) and some folk who handled guns all their life were forever mediocre, then there were those who just could not shoot well.

Agreed. Also 99% of all women I've seen behind a rifle are better shots than most men. Myself included, although I can give the broadside of a barn hell at 50yds

I wonder if the caliber choice is important?

It's hard to break folks of bad habits if they dont have habits you can teach them the proper habits its amazing to witness too

If money was no object....
https://www.tracking-point.com/weapons/shadowtrax6-6-5-creedmoor-bolt

or better yet...

https://www.tracking-point.com/weapons/shadowtrax8-338

This. I'm sure an instructor would go nuts trying to break me of all of my bad shooting habits. A good friend of mine's daughter is a flat out killer at long range, and has been dropping deer in their tracks out to 500 yards from the day she started hunting. He bought her a 7-08 which she doesn't use. She always wants to use daddy's 30-378 Weatherby magnum. I told him he will have to just give her that gun.

150 yards trotting right to left broadside. Dogs were barking at this big male today and he wasn't scared of them at all. He was in the pasture with the cows and I had to wait a while to get an all clear angle. Felt very good as the trigger broke and he was DRT. I hate these things and they are really getting brave around folks and animals.

I have the feel good effect on for today after missing the small female on Saturday. Now I have to cross the creek to get him out of the pasture.

B

Sight in at a known distance (100 Yards is always a good start), know the trajectory of your gun, have a good idea of your target distance, cross wind can be a problem, have a good rest, and squeeze the trigger ever so gingerly....every mistake is magnified at distance.

as a FBI trained Firearms Instructor I taught a LOT of folks for many years. Easiest to train to shoot GOOD is someone who has never shot a gun before. Worst set those damn idiot cowboy wanna be's

OP needs to take a .22 and LEARN how to shoot a rifle. Offhand at 20 yards at 1/2 targets 90% of the shooting. Thats is how I trained when I shot on the State Police rifle team. Rarely shot a big gun.

most important is to separate the trigger pull nerves from the ones that control the rest of the arm and hand. Hard wire that single nerve.

this is the biggest factor right here you'll be surprised at how much better you can shoot with a crisp 2.5lbs pull compared to the sloppy 5-7 lbs some off the shelf rifles have. the more force you use to pull the trigger the more you pull the shot off target.

Great tip. And HARD to learn. Its easy to torque the grip with your thumb and fingers as you squeeze the trigger. I try to keep my fingertips off the grip and just use the second joint of my fingers to apply pressure to to front of the grip and pull the stock back into my shoulder with consistent pressure. I just gently lay my thumb on top or to the side of the grip with little to no pressure.

I remember the first time I went shooting with my wife. Let's just say I drove home in humility. I later found out she was on the rifle team in school. I jerk the trigger and it drives her nuts.

I was at an indoor range in Tuscaloosa on night. There was one of those hot shot cowboys and his buddies shooting beside us. He talked his 19 year old girlfriend into shooting his 357mag with HOT loads for her first ever shot with any gun. Scared the crap out of her and they laughed their asses off. She was mad and sat down. I let her stew for ten minutes and then told her to try my gun, I had to promise her it wouldn't scare or hurt her. Pre War Colt Woodsman with std velocity shells. She agreed to try it and within ten minutes had shot up 50 rounds. I gave her another box AND a brief form shooting lesson. After that box I gave her my S&W66 and a box of wadcutters and another lesson. Halfway thru that box her boyfriend couldn't stand it and came over and asked if she could hit anything....I pulled her target and it was way better than his target. He shut up and went back to shooting. Girlfriend shot up another box of wadcutters. I told her she needed a new Colt Diamondback .38 from her idiot boyfriend to make up for his being an azzhole.

I love to take my wife to the pistol range and watch her out shoot the guys.

Adjustable shooting stick at the butt can also help you(if you have the time)